It may depend on whether you buy with Linux support in mind (having waited for someone else to do the spadework, and posted the results to Ubuntu Forums or wherever). There are machines where everything really does Just Work, with at most a few proprietary drivers that are in most distribution repos. (And I've had models from several manufacturers needing at most minor tweaks going back ten years or so --- FWIW, one machine that needed custom scripts to get the display-dimming function keys to work right.)

But if you buy on raw hardware specs, and then try to get Linux working after that, odds are that you'll run into something (sleep/wakeup issues, flaky Broadcom wireless drivers, or lately, problems with fussy trackpads) which will be real trouble.

So, you can get a pretty trouble-free Linux experience, if you do research --- but it might not be the exact machine you want, and it probably won't be anything bleeding-edge.